Dialdehyde starch-melamine derivatives



United States Patent Ofi 3,321,329 Patented Feb. 13, 1962 This inventionrelates to new derivatives of 2,3-dialde-o hyde starch and melamine orsubstituted melamines which may be designated aspolyglucosylol-melamine" compounds, and a process for making thesederivatives.

The novel compositions of this invention are prepared by the reaction of2,3-dialdehyde starch (also called periodate oxidized starch, or, inshort, oxystarch) with melamine or derivatives of melamine, such asbenz'oguanamine, N,N-diallylmelamine, and the like. This reactionproceeds in accordance with the following equation:

cn, on

CH BC wherein R is an amino, a phenyl, or an aminodiallyl radical, and xstands for the number of repeating units in the molecule, which maynumber as many 'as several thousand.

As illustrated by the above graphic formula of the reaction product, onemolecule of the given melamine compound reacts with one of the twoaldehyde groups of most of the dialdehyde polymer units. This mode ofreaction is borne out by gravimetric and nitrogen analyses as well'as bya determination of the remaining potential carbonyl content and isfurther substantiated in prior art literature. For example, theexistence of this type of slurry form. Melamine or its derivative thenreacts with oxystarch at temperatures of between 50 to 110 C. in from 1to 4 hours. The preferred acidic catalysts are sulfuric and aceticacids. As organic solvents, alcohols, preferably n-butanol, and ethers,preferably dioxan, and mixtures of these with water may be used tofurnish the .reaction medium. Significantly, this reaction mediumformation of resinous by-products and (2) the final prod functionssimultaneously both as solvent for the melamine reactant and asdispersing agent for 2,3-dialdehyde starch.

Two appreciable technological advantages inhere in the use of the slurryprocess described above: (1) there is no nets are almost homogeneous;that is, they containno crystalline materials as shown by microscopicexamination.

" The dialdehyde starch used as starting material for thispolyglucosylol-melamine compound may be conveniently and economicallyprepared by the electrolytic procedure disclosed in U.S. Patent No.2,713,553. It may also generally be made by the well known chemicaloxidation of starch with periodic acid. The above mentioned melaminecompounds are commercially available. The new melamine-modifiedoxystarch polymers can be recovered as amorphous white powders throughthe steps of direct filtration, washing with water, methanol or acetoneor other suitable solvents or mixtures thereof to' remove unreactedmelamine (derivatives) and drying I intra-molecular.

in an oven for several hours. The desired final products are insolublein water, aqueous mineral acids and most organic solvents, but arepartially soluble in aqueous sodium hydroxide, bisulfite and ammoniumhydroxide at ordinary temperatures and completely soluble with slightheating. Their reduced solubility in mineral acids as well as theirincreased stability, as compared with dialdehyde starch, are believed tobe due to the formation of cross-linkages, which may be inter-molecularas well as Corresponding methylene configura-' tions in a certainpercentage of the polymer units may also exist due to dehydration. Onthe whole, it must be appreciated that the exact nature of the interandintramolecular arrangements are difficult to establish.

The subject compounds of this invention have utility in the plasticsindustry as molding powders, in the textile industry for yielding creaseand crush-proof fabrics; and also in the surface coatings, laminatingresins, and paper resins industries. These compounds are also useful aschemical intermediates.

molecular structure, which results from an addition -reaction with onlyone aldehyde group, was stipulated for a urea derivative by I. W. Sloan,et al. in Ind. & Eng. Chem. v. 48, p. 1169, 1956, and for aphenylhydrazine derivative by L. Mester I. Am. Chem. Soc. v. 77, p.5452, 1955. Also, the solubility of the subject compounds in aqueousbisulfite solutions under short heating indicates the presence of thefree potential carbonyl groups.

The subject compounds are prepared in accordance with the followingprocedure:

The melamine in the form of its acetate or the desired substitutedmelamine is dissolved at elevated temperatures in water or in a suitableorganic solvent which is completely or partially water-miscible. Upondissolution of the melamine compound, oxystarch and an acidic catalystare added under stirring to give a reaction mixture in Although thisspecification is concerned with a method of reacting oxystarch withmelamine and substituted melamines, it is to be understood that thescope of this invention encompasses reactions of otheroxypolysaccarides, such as oxycellulose and the like, withmono-substituted melamines having substituents different from thosementioned above as well as diesubstituted melamines, the limitationbeing that the melamine compounds contain at least one free amino group.

The novel compositions of this invention and the process for theirpreparation may be more clearly explained with reference to thefollowing illustrative examples:

' .EXAMPLEI Reaction of 2,3-dialdehyde starch with melamine (2,4,6-triamino-s-triazine) (l) 26 g. (.205 mole) melamine. (2) 450 ml. water.(3) 50 ml. glacial acetic acid. (4) 24.7 g. oxystarch (assay 73.3%,14.7% moisture):

16.1 g. pure oxystarch=0.1 mole.

(1), (2) and (3) were charged to a 1 liter beaker equipped with astirrer and thermometer. While stirring rapidly, the mixture was heatedto C., the temperature span-s29 continuously for two hours, 'a-fterwhich time the mixture had a final temperature of 30-35 C; nwas thenfiltered and washed with"20% aqueous acetic acid to *rem'ovetheunreacted melamine (The excessof melamine used'can' be recoveredbyneutralizing the mother liquor with-sdium hydroxide). The-filteredpolyglucosylol-melamineacetate was dispersed in 200 ml. of water and,under stirring, was neutralized with sodium hydroxide solution. The freebase was filtered, washed with Water-and methanol, followed by Washingwithaceto'ne and then dried at 50 60 C. Yield: 36 g. (100% of-theor'y).Anal. calcd. for a 11.3% moisture-containing product obtaine'd'from astartingmaterial with 73.3% content of oxystarch: N, 19.0. Found: 'N,20.5. Carbonyl content found: 34.4.

EXAMPLE II Reaction of 2,3-dialdehyde starch with benzoguanamine(2,4-a'iamin0-6-phenyl-s-triazine) (1) 21.5 g. (.117 mole) benz'ogua'naitnine. (2) 300 mL-n-butdnol. V 7 (3) 0:5 rnLsulfuric acid (50% (4) "22.5 g. oXystarch (assay 73.3%, moisture 14.7%)":

' 14.2 gL'pure oxy'st'arc'h=0.09lmole.

(1), (2 and meat banged- 0a son "m1. three necked fiask equipped with astirrer, thermometer, and reflux-condenser, andheatedat I -I O" until(1) was completelydisso'lved, Then -(4 was charged to the flaskandwithout f further heating, under rapid stirring, the,

slurry was allowed t o cool slowly. At 40' C (after 1 hour) theslurrywas separated by filtration. The solid was washed with 50 ml.methanol/acetone (1:1), to re'moye unreacted benz oguanamine followed bywashing with acctone and was then dried. Yield: 39g. (103% of theory).Anal. calc'd. for a 3.5% moisture-containing product obtained from astarting material with 73.3%

content of (mg/starch; N, 14.2. Found: N, 16.3. Carbouyl content found:30.3.

EXAMPLE III Reaction of 2,3-dialdehy' de Sm-rah "w'ith MN'diallylmelarhilie (2,4-i1'idmin0 6-diallyldhiifio s-triazirie) (1) 28.8g. (.140mole) N,N-diallylmelamine; (2) 80ml. dioxan. (3) 20 ml. water.-(4) 1 ml. sulfuric'acid- (50%).

(5)121): g. oxystarch (assay 73;3%,14.7% moisture):

7.5 g. pure oxystarch=.047 mole.

(1), (2), (3) (4) and (5) were charged to a"250ml. three-necked flaskequipped with a stirrer, thermometer, and'reflux condenser. Theslurry'was then heated for 4 houratf50=60 C. on a'waterfbath. Aftercooling at room temperature, 100 ml. acetone wasadded to facilitate"quantitatiye precipitation and better filtration of the partially dispersed colloid polymer. The precipitate was filtered, washedwith acetoneand then 'driedat room temperature. Yield: 20 g. (100% of theory). Anal.calcd. for' a w 5.1% moisture-containing" product' obtained from astarting material with 73.3% content of'oxystarch: N, 159. Found: N,14.9.

In summary, the ihstant' inyntion pertains to novelmelamine-oxystarchpolymers obtained byreacting 2,3-

dialdehyde starch with melamine or substituted melamines in theproportion of l mole er the melamine compound per mole of 2,3-dialdehyde starch polymer units in the presence of a suitable-reactionmedium and an acidic catalyst, preferably sulfurico'r acetic acids. Thisreaction proceeds at temperatures of from 50-l10 C. in 1 to'4 hour's'.

1. A condensation product obtained by reacting in slurry a dialdehydepolysaccharide with an amino triazine selected "from the groupconsisting of melamine, benzoguanarnine and N,N-diallylmelamine in thepresence of an inert reaction medium'selected from the-group consistingof water, n-butanol, dioxa'n, and mixtures thereof, and an acid catalystselectedj'frorn th'e'group consisting of s'ulfuric ac'id and aceticacid,-at'a'temperature of about from 50 C. to C. for aboutfrom l to4-hou'rs.

2. A condensation product according-to claim 1 wherein the'dialdehydepolysaccharide is-dialdehyde starch.

3. A condensation :product obtained by reacting in slurry dialdehydestarch with melamine in the presence of an inert reaction mediumselected from the group consisting of water, n-butanol, dioiran, andmixtures-thereof, and an acid catalyst selected from the groupconsisting of sulfuric acidand acetic acid, at a temperature of aboutfrom 50 C. to 110 C. for about from 1 to 4 hours; a

4. A condensation .p'roductobtained/by reactingin slurry dialdehydestarch with be'nzoguahamine in the presence of an inert reaction mediumselected from'the group consisting of water, n-butanol, dioxan, andmixtures thereof, and an acid catalyst selected from the groupconsisting of sulfuric acid and-acetic acid, at a temperature of aboutfrom 50 C. to 110 C. for about from 1 to 4 hours.

5. A condensation product obtained by' reacting in slurrydialdehydestar'ch with N,N-diallylmelamine in the presence of an inertreaction'medium selected from the group consisting of water, n-butanol,dioXan, and mixtures thereof, and an acid catalyst selected from thegroup consisting of sulfuric acid andacetic acid, at 'a temperature ofabout-from 50 C. to .110 C. for about from 1 to 4 hours.

References Cited in the file of this patent UNITED STATES PATENTS OTH RREFERENCES, Jackson et 'al.: Journal of the "American Chem. Soc., vol.59, pages 2049-2050 (1937).

' Sloan et al.: Industrial-and Engineering Chemistry, vol. 48, pages1165 1172 (1956).

1. A CONDENSATION PRODUCT OBTAINED BY REACTING IN SLURRY A DIALDEHYDEPOLYSACCHARIDE WITH AN AMINO TRIAZINE SELECTED FROM THE GROUP CONSISTINGOF MELAMINE, BENZOGUANAMINE AND N,N-DIALLYMELAMINE IN THE PRESENCE OF ANINERT REACTION MEDIUM SELECTED FROM THE GROUP CONSISTING OF WATER,N-BUTANOL, DIOXAN, AND MIXTURES THEREOF, AND AN ACID CATALYST SELECTEDFROM THE GROUP CONSISTING OF SULFURIC ACID AND ACETIC ACID, AT ATEMPERATURE OF ABOUT FROM 50*C. TO 110*C. FOR ABOUT 1 TO 4 HOURS.